cb.reset.parameters(new_params)
nrounds
to be set at each iteration,
or a function of two parameters learning_rates(iteration, nrounds)
which returns a new parameter value by using the current iteration number
and the total number of boosting rounds.Note that when training is resumed from some previous model, and a function is used to
reset a parameter value, the nround
argument in this function would be the
the number of boosting rounds in the current training.
Callback function expects the following values to be set in its calling frame:
bst
or bst_folds
,
iteration
,
begin_iteration
,
end_iteration
.
callbacks